Manufacture of oil-soluble polyhydric phenols



Patented Dec. 8, 1936 PATENT "OFFICE MANUFACTURE OF OIL-SOLUBLEPOLYHYDRIC PHENOLS Charles P. Wilson, In, Houston, Tex.

' No Drawing.

Application May 29, 1934,

Serial No. 728,086

17 Claims.

This invention relates to a method of preventing deterioration of oils,fats, and rubber, and is applicable to substances liable to oxidation.The process and product will be described more particularly in relationto inhibiting auto-oxidation of motor fuels resulting from pyrolysis ofheavy oils or coal.

Color deterioration and gum formation are known to be the result ofoxidation. Color deterioration does not render motor fuel or motor oilunfit for use, but lowers its market value. Gum formation is the resultof oxidation of unsaturated hydrocarbons, and when present in motor fuelin small quantities renders the fuel unfit for use in an internalcombustion engine. To obtain gum-free and stable products, the usualpractice is to remove a substantial quantity of the unsaturatedhydrocarbons through treatment with sulfuric acid, or through thecontrol of the cracking plant in such a manner as not to produce a highconcentration of the unstable unsaturated hydrocarbons. Control of thecracking process in this way sometimes results in a lower percentage ofcracked fuel, and the sulfuric acid treatment always results in a loss,which in many cases runs as high as of the motor fuel produced. Thistreatment is costly and wasteful, and also results in a lowering of theanti-knock value of the motor fuel.

The primary object of the invention is the manufacture and use of anoxidation inhibitor which, when added in minute quantities, preventsdeterioration of hydrocarbons and various oils liable to oxidation. Itis particularly useful in the manufacture and marketing of motor fuelcontaining unsaturated hydrocarbons liable to oxidation, since it notonly inhibits gum formation in storage, but actually reduces the gumyield when the cracked product to which the inhibitor has been added istested for gum by the copper dish method. In the majority of cases onlya minute quantity of the inhibitor, the cost of which is almostnegligible, is required to reduce the result of the copper dish test toany desired specification. Results of tests made with identical crackedgasolines with and without the addition of the stabilizing compound areshown hereunder:

COPPER DIsB: Tasrs Sample 1 Amount of inhibim added f g (gins. per 100cc.)

Ni] 0.10:; 0.002 0. 04s 0. 005 0. 00s 0. 01s 0. 0%

Sample 2 Nil 0.183 o. 0007 0.101 0. 0014 o. 066 0. 0035 0. 008 0.0070.011

I have found that the following substances are effective in preventinggum formation when added in minute quantities to oils:

Pyrogallol Para-aminophenol Catechol Para-phenylene diamine HydroquinoneMethylaminophenol Ortho-aminophenol A1pha-naphthol Numerous othercompounds, such as cresol, dimethylaniline, etc., have a slightstabilizing effect, but my experience has been that as a general ruleonly aromatic compounds with two bydroxyi and/or amino groups in theortho or para positions of the benzene ring will completely preventoxidation, although it will be noted that alpha-naphthol, which has onlyone hydroxyl group, is an exception. The presence of other groups in thebenzene ring in addition to the above mentioned does not destroy theinhibiting action.

All of the above mentioned substances except alpha-naphthol are moresoluble in water than in oil, in which they are nearly insoluble, and

they are not satisfactory for use in practice for the commercialstabilization of motor fuels on account of the fact that it is diflicultto prevent the latter from coming into contact with water. Naphtholcannot be used, since it causes motor fuel to deteriorate in color,although it is satisfactory as regards solubility.

I have found that if an alkyl or aryl group is substituted for ahydrogen atom in these compounds, their solubility in water is decreasedand their solubility in oil is increased without an appreciable loss intheir power to inhibit oxidation. The greater the number of alkyl oraryl groups which can be substituted in the benzene ring, the moresoluble is the resulting compound in the hydrocarbon to be stabilizedand the less soluble in water.

The new and novel features of the present invention are: the productionof oil-soluble oxidation inhibitors from certain ty es" of oil-insolublephenolicor amino compounds, by substitution of one or more alkyl or arylgroups for hydrogen atoms; an improved method of introducing an alkylgroup into a phenol; and the utilization of turpentine, a liquid sulfurdioxide extract of an oil, or the unsaturated hydrocarbons derived fromthe pyrolysis of oil or coal tar distillates, such as crude benzol orsolvent naphtha, as the base or stock from which the substitutedphenolic or amino compound is produced; oils containing mixedunsaturated hydrocarbons are very much cheaper than the pure unsaturatedcompounds, but are equally satisfactory for the preparation of thesubstituted compound.

The introduction of alkyl groups is effected by a modification of themethod of Koenigs (Ber. 23, 3144; 24, 179, 3889; 25, 2649) who preparedalkyl substituted phenols by allowing a mixture of one part of thephenol with the equivalent amount of an unsaturated hydrocarbon to standfor several days in the presence of one part of concentratedsulfuricacid and nine parts of acetic acid. My improvements that are newto the art are as follows:

1. The use of a mixture of unsaturated hydro-- carbons, such asturpentine, a liquid sulfur dioxide extract of an oil, or an oil derivedfrom the pyrolysis of oil or coal. Such oils should preferably contain alarge percentage of unsaturated hydrocarbons, as high concentrations ofthe latter cause the reaction to take place more readily.

2. The use of dilute sulfuric acid (about 50%) instead of concentratedacid. This prevents loss of the phenolic compound by eliminating sidereactions such as the formation of acetates.

3. The use of a much smaller quantity of sulfuric and acetic acid, thusreducing the cost of solution of alkyl substituted phenol.

manufacture.

4. Carrying out the reaction at an elevated temperature with agitation.This reduces the time required to a few hours.

5. The use of a considerable excess of unsaturated compounds, in orderto avoid loss of the more costly phenol.

6. Incomplete removal of acetic acid from the A trace of acid present inthe solution acts as a preservative, preventing oxidation of thecompound itself before it is added to the oil to be stabilized.

7. The use of a dilute solution of a mineral acid for extracting theacetic acid instead of water or ammonium carbonate. Oxidation of thecompound during the washing is thus prevented.

It will be noted that by alkylation of the various oil-insolubleoxidation inhibitors, such as pyrogallol and aminophenol, in variousways, an almost infinite number of different compounds can be obtainedwhich would be suitable for inhibiting the oxidation of oils. For thepreparation of the various types of compounds, a number of differentmethods are available. For example, amyl pyrogallol may be prepared bythe action of amyl alcohol on pyrogallol in the presence of anhydrouszinc chloride; and aminophenol can be alkylated by heating underpressure with alcohols; or the reaction between pyrogallol andunsaturated hydrocarbons will take place to some extent without acatalyst, or with aluminum chloride. I have, however, found that thecheapest and easiest compounds to manufacture are those prepared frompyrogallol by the method described above. Catechol also gives goodresults by this method, but is more expensive. Examples of the preferredmethod of preparation using cracked distillate, crude benzol, andturpentine are given below:

Five parts by weight of powdered pyrogallol, ten parts of glacial aceticacid, one part of 50% sulfuric acid, and ten parts of cracked distillateare placed in an acid-resisting container fitted with a stirrer and areflux condenser, and supplied with facilities for heating. The mixtureis agitated violently, and heated to boiling. The agitation and heatingare continued for two hours, 75 parts of cracked distillate beinggradually added during this period. After two hours, when substantiallyall of the pyrogallol should have entered into combination with theunsaturated hydrocarbons present, the agitation is stopped and theproduct allowed to cool in an oxygen-free atmosphere. The reaction whichoccurs is probably as follows:

R.CH.CH2 plus CeHa(OH)a oleflne pyrogallol RCH2.CH2.C6H2 (OH) astabilizer The resulting mixture consists of a solution of the oxidationinhibitor and acetic acid in the oil which supplied the unsaturatedhydrocarbons, and a layer of sludge on the bottom of the containingvessel. Twenty parts of 0.1% sulfuric acid are introduced, and themixtureis agitated for fifteen minutes for the purpose of removingexcess acetic acid. The washing also causes any substituted compoundcontained in the sludge to return to the oil solution. The lower layeris drained ofl, and the extraction repeated twice. The solution ofoxidation inhibitor thus prepared is then run into a storage vessel,preferably of copper or wood.

When using crude benzol, five parts by weight of powdered pyrogallol,ten parts of glacial acetic acid, one part of 50% sulfuric acid, and tenparts of crude benzol are placed in an acid-resisting container fittedwith a stirrer and a reflux condenser, and supplied with facilities forheating. The mixture is agitated violently, and heated to boiling. Theagitation and heating are continued for two hours, 175 parts of crudebenzol being added gradually during this period. After two hours, whensubstantially all of the pyrogallol should have entered into combinationwith the unsaturated hydrocarbons present, the agitation is stopped andthe product allowed to cool in an oxygen-free atmosphere. The resultingmixture 2,oes,212

consists of a solution of the oxidation inhibitor and acetic acid in theoil which supplied the unsaturated hydrocarbons, and a layer of sludgeon the bottom of the containing vessel. Twenty parts of 0.1% sulfuricacid are introduced, and the mixture is agitated for fifteen minutes forthe purpose of removing excess "acetic acid. The

washing also causes any substituted compound contained in the sludge toreturn to the oil solution. The lower layer is drained oif, and theextraction repeated, twice. The solution of oxidation inhibitor thusprepared is then run into a storage vessel, preferably of copper orwood.

When turpentine is used, forty parts of pyrogallol are dissolved byheating and agitation in sixty parts of glacial acetic acid. One part of50% sulfuric acid is added, and a hundred parts fresh turpentineintroduced while the mixture is being agitated. Heat is evolved, andcare must be taken that the temperature does not rise above 100C. Whenall the turpentine has been added, the mixture is maintained at about 90C. until the reaction is substantially complete. After cooling, it maybe diluted by a suitable oil. It is then washed as in the previousexample. The amount of the substituted compound formed is substantiallytwice the weight of pyrogallol used. I have found that acetic acid actsas a preservative of the compound, but most of it must be removed, as itwould cause the motor fuel to which the above described inhibitor hadbeen added to become corrosive. The acetic acid may be removed byextraction with any suitable solvent, such as water or a mineral acid orby other suitable methods such as distillation, instead of by dilutesulfuric acid as described in the above examples.

It has been found that the substituted compound when prepared asdescribed above may be stored for a long period of time, at least aslong as two years as shown by practical tests, without losing activityas a stabilizer,

I have found that a compound as thus prepared is acidic and that it canbe removed or destroyed by shaking with alkalies, such as sodiumcarbonate or caustic soda. It is, therefore, necessary to prevent themotor fuel from coming into contact with alkaline substances after theaddition of the inhibitor. The compound is also destroyed by organicperoxides, and to prevent this the motor fuel must be perfectly freshand free from peroxides when the compound is added.

The gum content of Samples 3 and 4 shown hereunder has been determinedby the U. S. Bureau of Mines steam oven method, in which a 20 cc. sampleof motor fuel is evaporated in a steam oven from which oxygen isexcluded. The gummy residue obtained in this manner is considered torepresent the actual or inherent gum present in the fuel.

The gum content of Samples 1 and 2 hereinbefore described under copperdish tests was determined by evaporating 100 cc. of cracked gasoline ona steam bath. In this test the gasoline is exposed to atmospheric oxygenduring the evaporation and although a. sample of cracked gasoline givesa considerable residue by this method, the same sample might be found tobe entirely free from inherent gum as determined by the steam ovenmethod.

Results of storage tests made on identical cracked gasolines, with andwithout addition of inhibitor, are given below. The samples consist ofcracked gasoline stored in dark in glass bottles vented to atmosphere.

Sample 3 SW Oven gum Color Saybolt chromometer 20 cc.) Time of storageWithout With 0.001% Without With 0.001%

inhibitor inhibitor inhibitor inhibitor 1 Nil Nil Plus 25 Plus 25 Nil 2525 gin 25 25 ii 25 25 Ni] 25 25 Nil 25 25 Nil 25 25 Nil 17 25 Nil 25 Ni]25 Ni] 24 Nil 22 Nil 2?. Nil 2a Nil 25 016 .018 23 Sample 4 Without With0.00o% Without With 0.o005% inhibitor inhibitor inhibitor inhibitor NilPlus 25 Plus 25 Trace 25 25 Trace 25 25 001 25 25 .006 25 25 22 25 21 2542- 24 48 24 54 2a 00....... 21 71. a3...

From the description it will be evident that while I have described andclaimed the preferred embodiment of the invention, it is to beunderstood that I reserve the right to make all changes properly fallingwithin the spirit of the invention and without the ambit of the priorart.

This application is a continuation in part of my application, Serial No.503,095, filed December 1'7, 1930.

I claim:

1. A process for the manufacture of oil-soluble phenols, which comprisescondensing a light coal tar distillate with a phenol in the presence ofa dilute mineral acid condensing agent.

2. A process for the manufacture of oil-soluble phenolic compounds,which comprises reacting a polyhydric phenol with a light coal tardistillate while in the presence of a dilute mineral acid condensingagent.

3. A process for the manufacture of oil-soluble phenolic compounds,which comprises reacting a trihydric phenol with ingredients of a lightcoal tar distillate while in the presence of a dilute mineral acidcondensing agent.

4. A process for the .manufacture of oil-soluble phenolic compoimds,which comprises chemically combining a polyhydric phenol, havinghydroxyl groups in the ortho position, with a light coal tar distillatewhile in the presence of a dilute mineral acid condensing agent.

5. The process according to claim 4 in which the polyhydric phenol ispyrocatechol.

6. A process for the manufacture of oil-soluble phenolic compounds,which comprises chemically combining a polyhydric phenol, havinghydroxyl groups in the para positions, with a light coal tar distillatewhile in the presence of a dilute mineraiacid condensing agent.

'7. The process according to claim 6 in which the polyhydric phenol ishydroquinone.

8. A process for the manufacture of oil-soluble phenolic compounds whichcomprises reacting pyrogallol with crude benzol while in the presence ofacetic acid and a small amount of sulfuric acid.

ents of a light coal tar distillate as substituted hydrocarbon groups.

11. A mixture of oil-soluble polyhydric phenol derivatives consistingessentially of a polyhydric phenol condensed with a light coal tardistillate, said derivatives containing ingredients of said distillatesas substituted hydrocarbon groups.

12; A mixture of oil-soluble phenolic compounds consisting essentiallyof a trihydric phenol condensed with ingredients of a light coal tardistillate, said compounds containing ingredients of said distillates assubstituted hydrocarbon groups.

13. A mixture of oil-soluble phenolic compoTmds consisting essentiallyof substituted polyhydric phenols, having hydroxyl groups in the orthoposition, and containing hydrocarbon components of a light coal tardistillate as substituted hydrocarbon groups. I

14. A product according to claim 13 in which the polyhydric phenols aresubstituted derivatives of pyrocatechol.

15. A mixture of oil-soluble phenolic compounds consisting essentiallyof substituted polyhydric phenols, having hydroxyl radicals in the paraposition, and containing ingredients of a light coal tar distillate assubstituted hydrocarbon groups.

16. A.product according to claim 15 in which the polyhydric phenols aresubstituted derivatives of hydroquinone.

1'7. A mixture of oil-soluble phenolic compounds consisting essentiallyof pyrogallol derivatives containing hydrocarbon ingredients of crudebenzol as substituted groups.

CHARLES P. WILSON, JR.

